1. Field of the Invention
This invention relates to ceramic stationary components for a gas turbine engine and more particularly to structure for mounting such ceramic components.
2. Description of the Prior Art
It is well known that the use of ceramic components within the path of the hot motive fluid in a gas turbine engine would permit the motive fluid to be at a higher temperature than presently available when such structure is fabricated from a high-temperature alloy material. Further, if cooling air is supplied to the structure to permit raising the temperature of the motive fluid beyond the temperature limitations of the material, it is apparent that because of the ability of ceramics to withstand the higher temperatures, less cooling fluid would be required when the components are fabricated from ceramic materials and thus the turbine efficiency would be improved.
However, as opposed to the high-temperature metal alloy material, ceramic components are quite brittle and therefore care must be taken in designing them to minimize stress concentrating features and providing a configuration which is relatively easily fabricated through the well-known isostatic densification process for producing generally fully dense high strength ceramics. Further, in mounting the ceramic components within a gas turbine, consideration must be given to mounting them in a manner to minimize vibrations. This is particularly true for the stationary components which, unless firmly held, will be vibrated by the force of the hot motive gas passing thereacross. The mounting structure must be able to accommodate distinct variations in the rate of expansion between the ceramics and the supporting elements, generally made of metal, due to their different temperatures and to their different coefficients of expansion. Thus, it is apparent that the mounting support for ceramic components must be unique to the ceramic and metal interface to satisfy these requirements.
U.S. Pat. No. 4,008,978 shows a gas turbine with ceramic components disposed in and forming the motive gas path; however, the support system for the components as shown therein is considerably different than the support for the components according to the instant invention.